Filter Objects

A filter object is a COM object that implements the IFWXFilter interface. Each application
filter must include a filter object. The names of filter
objects typically include the word Filter. When the Microsoft
Firewall service starts, it creates an instance of the filter
object for each application filter that is installed on the ISA
Server computer and enabled. The Firewall service uses the
implementation of the IFWXFilter interface on each filter
object to initialize the application filter, to create session filter
objects, and to initiate the shutdown procedure that
destroys the filter object when the Firewall service is stopped.
The initialization process can also include the creation and
initialization of other COM objects that are used in the
application filter.